Greenfield Tornado: One Of The Fastest Tornado In History

The Greenfield tornado was clocked by a radar truck at up to 318 mph. So why is it officially only an EF4? On May 21, 2024, a research radar parked beside Greenfield, Iowa caught one of the three fastest tornado winds ever measured. We follow the storm from the sky that built it to the one minute it spent in town, the school-book page that landed 90 miles away, and the rating question that still isn't settled. Then a 2025 tornado in North Dakota turns the whole thing upside down. Chapters 0:00 318 mph, officially an EF4 0:52 The sky that built it 2:18 Touchdown and the radar trucks 3:32 The wind farm that hid a clue 5:22 One minute in Greenfield 6:12 3:41:08 PM, the reading 6:43 What the minute left behind 7:26 A page found 90 miles away 8:04 Why it's only an EF4 10:03 The inconceivable tornado 10:54 The Enderlin twist 11:35 Corn nobody planted 12:23 One mph short Sources NWS Des Moines, May 21, 2024 Iowa Tornadoes, Winds, Flooding: https://www.weather.gov/dmx/2024-May-... NWS Des Moines Public Information Statement, May 23, 2024: https://mesonet.agron.iastate.edu/api... American Meteorological Society, "BEST: Capturing the Worst Tornado Winds" (2024): https://headlines.ametsoc.org/2024/07... Wurman & Kosiba, "Radar Determined Intense Tornado Frequencies, Wind Profiles and the BEST Tornado Study", ECSS 2025: https://doi.org/10.5194/ecss2025-273 Kosiba & Wurman (2023), "The strongest winds in tornadoes are very near the ground", Communications Earth & Environment Associated Press, May 2024 (turbines, debris found up to 100 miles away, the page in Ames): https://kmph.com/news/nation-world/5-... KCRG, "Meteorological Mysteries: The Greenfield Tornado's Effect on Wind Turbines" (2024): https://www.kcrg.com/2024/08/09/meteo... Associated Press, "Deadly North Dakota tornado upgraded to EF5, the first in US in 12 years" (Oct 2025): https://www.fox9.com/weather/deadly-n... NOAA Storm Prediction Center, Enhanced Fujita Scale: https://www.spc.noaa.gov/efscale/ T. T. Fujita (1971), SMRP Research Paper 91 (the original F-scale) Wikipedia, "Greenfield tornado" (timeline cross-check): https://en.wikipedia.org/wiki/Greenfi... #tornado #GreenfieldIowa #weather